1. ITERATORS
Acknowledgement: THE Slides are Prepared FROM SLIDES PROVIDED By NANCY M. AMATO AND Jory Denny

2. Standard Template Library
A general purpose library of data structures (containers) and algorithms communicating through iterators.
Plug each piece together and use in different applications.
#include <vector> #include <algorithm> int main(){ int myArray[4]={2, 8, 5, 3}; std::vector<int> v(myArray, myArray+4); std::sort(v.begin(), v.end()); }
vector
sort
container
generic algorithm
iterator

3. Containers
Container is an object storing other objects which can be accessed by iterators
Let 𝑋 be a container, then some important associated types:
X::value_type – type of data stored in the container
X::iterator – type of iterator for the container
X::const_iterator …

4. Containers Valid expressions 𝑎.begin – beginning of container
𝑎.end – one past the last element of container
𝑎.size – size of container
𝑎.empty – does the container have anything in it?

5. Iterators sort Iterators are used to point to other objects.
Iterators play an interface between data structures and algorithms
Main operations
advance(), next(), operator++
Dereference – operator∗(), operator→()
vector
sort
container
generic algorithm
iterator

6. Iterators Forward Iterator – Only allows traversal from begin to end
Bidirectional Iterator – Allows traversal in both directions (reversed order)
Random Access Iterator – arbitrarily access elements in any order
etc.
Algorithms are defined for certain types of iterators, i.e., sort is only defined for random access iterating

7. Example Create a vector containing integer values
int myArray[4]={2, 8, 5, 3};
std::vector<int> v(myArray, myArray+4);
Iterate over the vector and output each integer
for(vector<int>::iterator it = v.begin(); i != v.end(); ++it)
cout<<*(it);
Iterate over the vector using random access iterators to output each value
for(size_t i = 0; i < v.size(); ++i) cout<<*(v.begin() + i);